Ignition circuit breaker



Dec. 16, 1941. o. H. BRAUER IGNITION CIRCUIT BREAKER Filed Aug. 1, 1940 INVENTOR. OTTO H. BRAUER 6i 4 L444 ATTORNEY.

Patented Dec. 16, 1941 UNITED STATES. PATENT OFFI IGNITION cmcnrr BREAKER Otto H. Braucr, Three Rivers, Mich, assignor to Fairbanks, Morse & 00., Chicago, 11]., a corporation of Illinois Application August 1, 1940, Serial No. 349,180

4 Claims. (01. 206-30) .type above briefly referred to, a breaker arm which is of laminated construction, consisting essentially of a leaf spring, the leaves of which are reasonably tempered and resilient, and which are of a good conducting metal. However, after a certain period of service some difllculty has been encountered in an undue extent of breakage of one or more of the leaves of a laminated breaker arm of the type referred to, such breakage occurring near or in the zone of clamped securement, say of one end of the arm. Some-- times, also, breaker arms of leaf spring construction have exhibited a tendency due to a rebound or swing action, to cause an untimed actuation of the breaker points, resulting in a waste spark, with obviously undesirable results. The correction of the above noted dimculties accordingly constitutes a major objective of the present invention.

Somewhat related to the foregoing generally stated objective, is that of increasing the life of presently preferred embodiment of the invention,

taken in connection with the accompanying drawing, in which:

Fig. 1 is an elevational view of a circuit breaker assembly embodying the present improvements, and Fig. 2 is a fragmentary, somewhat enlarged exploded view of the novel supporting-end assembly structure associated with the breaker arm.

Referring now by characters of reference to the drawing, the breaker assembly includes, and the remaining major elements thereof are assembled on, an elongate bracket member I, which is by preference formedof an insulating material, such as a hard fiber, or of Bakelite or other synthetic resinous or plastic material. The I bracket may however, be formed of metal, and suitably insulated from ground or from some of the circuit forming elements, according to the chosen circuit arrangement. The bracket may be mounted in any desired position, either horizontally, vertically or otherwise, adjacent to a fixed element'on or near the engine, as by suitable mounting screws l I. Assuming for purposes of description, a vertical mounting of the bracket 10, its upper end portion is of a generally inverted U-shape, pointed out by the numeral l2, one of-the depending legs of which is identified with the body of the bracket H, and the opposite shorter leg indicated at l3.

An adjustable contact point It projects inwardly of the longer leg of the bracket, and is mounted as through a threaded shank l5, threadedly engaging the bracket, and which carries a washer IS. The bracket III is drilled and tapped to receive the threaded shank It, as will be readily understood.- Carried externally of the bracket by the threaded shank are a pair of nuts or equivalent elements 20, preferably between which is disposed a terminal connector 2| carried by conductor 22, in one side or leg of the low side of the ignition circuit to be interrupted by the device. The circuit utilized is or may be conventional, and preferably of the type often used in which one side of the circuit is constituted by a ground through the metal parts of the engine and accessories, while the other leg of the circuit is insulated from the ground. It will have been observed from the arrangement of point It, and the threaded relation of shank l5 that through these parts l5-20, the setting of the point It may be varied'to care for initial and service adjustments, as well understood in the art.

Secured or anchored at its lower end, (when mounted in the vertical position shown), is the breaker arm 23 which consists in the form shown, of a plurality of resilient spring metal conducting strips 24, the strips 24 collectively constituting the breaker arm proper. This arm is assembled to a base portion 25 of the bracket Hi, this base being apertured as at 25 and 28 for the reception of holding screws 21 and 30. Cooperating with the base 25 for mounting of the breaker arm is a holding plate 3|, preferably of conducting material or metal, apertured to receive the screws 21 and 30, these apertures registering respectively with the openings 26 and 28. Of a size and shape conforming approximately to the rectangular outline of the holding plate II, are a pair of elements which may conveniently be formed of rubber sheet material of reasonable compres-.

' resilient properties.

sive resilience. and indicated, respectively, near. est the base 26, at 32 and on the opposite side of 'the arm at 33. These rubber cushions or pad elements are either apertured or formed up in separate strips on opposite sides of the screws, so that the assembly screws may be passed therethrough into the openings in the base portion 33.

The cushions or pad elements 32 and 33, hereprobably possess inherent insulating properties,

contacts are brought into circuit-closing position upon engagement of the nose 4! of the cam, with the breaker arm. The Purpose of the u-shaped portion l2-l3 about the free end of the breaker arm, is to preventundue swinging or rebound of the arm, it now being obvious that the depending leg-l3 will serve distinctly to limit the swing of the breaker arm,-in a circuit-opening" direction.

In breaker arms of leaf spring type the zone of most frequent breakage is as indicated, generally, by the numeral 43. It will have been observed from the foregoing description that, as the leaf spring arm is flexed in either direction from its normal plane, it is cushioned by one or the other and since the breaker arm 23 serves to carry the ignition current to the point 36, it is desirable to assure completion of the circuit from the arm through to the circuit wiring, by the provision of a preferably doubled or folded plate or strip 43. This is conveniently formedof a thin strip of copper or bronze, folded about the outermost I. cushion or-pad '33 and apertured to pass holding screws 21 and 30. I t

The manner of assembly of the parts and their function in service will have become fully apparent from the foregoing description of elements, but it may be briefly noted for completeness,that"assemb1y of the breaker arm 23, carrying-contact point 36, is effected by placing one of therubber cushion elements such as 32 adjacent the base or block portion of the bracket, folo lowing which the plurality, say three, springblades or strips '24, collectively constituting the arm -23, are assembled over the cushion 32. The thin conducting strip 40 may then be folded over the second or outer rubber cushion such as 33, and this latter assembly placed over the breaker arm. The holding plate 3i completes the assembly of parts in this zone, and with the various screw openings of these elements brought to register, the screws 33 and 21 are inserted and securely threaded up. The screw 21, projecting through the base 25, is by preference, provided witha pair of holding nuts 4| which serve, besides their assembly function, to retain and perfect electrical connection with a terminal 42 for conductor 43. The latter, when the points 38 and I4 are closed, constitutes a continuation of the leg of the circuit identified with conductor 32 mentioned above. A final adjustment setting of the points i4 and 36, through the threaded shank it, places theassembly in operative condition.

It will be observed particularly from Fig. 1 that the breaker arm 23 is disposed adjacent an operating cam. 44 provided with'a protruding profile or nose portion 45. For certain yp s of service. an eccentric may'of course be substituted for the cam 44, the cam or eccentric being fixed on or-operated by a suitable engine-driven shaft,

and thus arrangedin operative or timed relation with the engine for the usual and well known purpose of ignition timing.

of the-pad element 32 or 33, according to the direction of actuation. The cushion elements, while enabling the screws -21 and 30 to be threaded up tightly, nevertheless yieldably embrace the fixed end of the breaker arm in a manner to prevent a sharp or closely defined zone of bending just above the base 25 and holding plate 3|, this now more elongate region of bending being provided for by the pad elements and hence extending ove a greater length of the anchored portion of the erm, than is the case without the use of the cushioning members. In practice the arrangement has been found to add considerably to the life of the leaf spring arms by lessening fatigue therein, and also has been found to prevent an undesired rebound or backswing of the arm upon its release by the cam 44. In all other respects 'the present improvements fully attain each of the objects above set forth.

Although the improvements have been de-' scribed by making specific reference to a preferred embodiment for a specified service, many changes are possible without departure from the full intended scope of the invention as defined by the claims hereunto appended;

I claim: '1. In an ignition circuit breaker, a breaker arm of spring-strip construction, means for periodi- It will be noted as a preference in connection with the present assembly that the arrangement of contact points 36 and I4 is such that the circult is normally open therebetween, and that the cally flexing the arm for-effecting the circuit opening and closing function thereof, circuit 618-.

ments cooperating with the arm and including breaker points, a holder for a relatively fixed portion of the arm, a cushioning element constitut ing a part of the holder, and arranged yieldabiy to oppose flexing movement of the arm, said circuit elements including a conductingcover for the cushioning element consisting of a thin flexible strip of conducting material.

2. man ignition circuit breaker, a breaker arm of spring strip construction, a cam engaging the arm for periodically actuating the same, a holder for a secured end portion of the arm and including a pair of cushioning elements respectively arranged for compression by the arm when the arm is flexed in opposite direction from its plane of repose, and circuit elements cooperatingwith the arm and including breaker points, one of whichv is carried by the arm.

3. In an ignition circuit breaker assembly, and in combination with the circuit-forming elements including a pair of ignition points, a

breaker arm constituting one of said circuit elements for actuation of the points, a cam engaging an intermediate point of the breaker arm, the breaker arm being constructed of a plurality of superposed spring strips. and mounted at one of its ends, a mounting assembly for said end of the arm including a mounting base, a pad of rubberlike material exhibiting reasonable compressive resilience, adjacent the base, a second pad or cushion element disposed on the opposite side of the breaker arm, a holding plate substantially coextensive with the cushions or pads between which the arm is yieldably gripped, holding screws extending through the plate, the cushion elements or pads and the secured end of the arm, the circuit iorming elements further including a. contact strip of relatively thin flexible conducting metal engaging opposite sides of the second said cushion or pad element to complete the circuit from the arm to said base, a terminal connection to said base, and a terminal connection to one of the points.

4. The combination in a circuit breaker assembly, with the circuit iorming elements thereof, of a leaf spring constituting a breaker arm and in circuit with said elements, a cushioning holder for the leaf spring including resilient pad elements on opposite sides thereof, a bracket for the assembly and holding plate, together with screws for securing one end of the breaker arm between the holding plate and bracket, substantially as 10 herein shown and described.

OTTO H. BRAUER. 

